Question: Solve the system of equations. $\begin{aligned} &-5x+4y = 3\\\\ &x=2y-15 \end{aligned}$ $ x=$
Answer: We are given that ${x}={2y-15}$. Let's substitute this expression into the first equation and solve for $y$ as follows: $\begin{aligned} -5{x}+4y &= 3\\\\ -5\cdot({2y-15})+4y&=3\\\\ -10y+75+4y&=3\\\\ -6y&=-72\\\\ y&=12 \end{aligned}$ Since we now know that ${y}={12}$, we can substitute this value in the second equation to solve for $x$ as follows: $\begin{aligned} x &= 2\cdot{y}-15 \\\\ x&=2\cdot{12}-15\\\\ x&=9 \end{aligned}$ This is the solution of the system: $\begin{aligned} &x = 9 \\\\ &y=12 \end{aligned}$